Anderson underwent surgery after injuring his knee in Buffalo's Week 5 loss to the San Francisco 49ers. The team was holding out hope he could return on Sunday against his former team, the New England Patriots.

Now Anderson goes into limbo. If he has a second procedure on the knee, Gailey expects him to miss another two-to-three weeks.

In other injury news, starting left cornerback Aaron Williams will miss some time after suffering a knee injury during Sunday's loss to the Houston Texans.

"It wasn't as bad as it could have been," Gailey said. "He's going to miss a few weeks, but it's not a season ender."

Williams was injured when Texans star Andre Johnson fell on his right leg after making a 34-yard reception in the second quarter. Williams underwent an MRI on Monday, which did not reveal any serious damage.